Impaired contact hypersensitivity to trinitrochlorobenzene in interleukin-4-deficient mice

Area of Science:

• Immunology
• Dermatology

Background:

• Contact hypersensitivity (CH) is an immune response to haptens.
• The role of endogenous interleukin-4 (IL-4) in CH is not fully understood.
• Trinitrochlorobenzene (TNCB) is a common hapten used to induce CH.

Purpose of the Study:

• To investigate the role of endogenously produced IL-4 in the CH reaction to TNCB.
• To determine if IL-4 acts during the induction or effector phases of CH.
• To explore the involvement of other Th2 cytokines in restoring CH.

Main Methods:

• Comparison of CH reactions in IL-4 genetically deficient (IL-4 KO) mice and wild-type (wt) mice.
• Induction of CH using TNCB.
• Restoration of CH reactions by administration of IL-4 or IL-13.
• Analysis of T helper type 1 (Th1) responses and Vgamma3+ cell accumulation.
• Assessment of mononuclear cell recruitment and vascular leakage.

Main Results:

• CH reaction to TNCB was abolished in IL-4 KO mice.
• IL-4 administration restored the CH reaction in IL-4 KO mice at both induction and effector stages.
• IL-4 KO mice showed reduced mononuclear cell recruitment and vascular leakage at the challenge site.
• IL-13, but not IL-10, restored the CH reaction in IL-4 KO mice.
• IL-4 was not required for CH response to oxazolone, indicating hapten specificity.

Conclusions:

• Endogenous IL-4 is essential for the CH reaction to TNCB.
• IL-4 acts as a proinflammatory mediator in CH, facilitating mononuclear cell accumulation and vascular leakage.
• The requirement for IL-4 in CH is hapten-specific.